CHAPTER LXII 
THE ORDER OF SHARKS 
SQUALI 
We have now reached the subclass of Carti- 
laginous Fishes. 
And what is a “ car-ti-lag'i-nous fish?” 
Cartilage is a bloodless tissue, commonly called 
gristle, flexible but not elastic, quite colorless, of 
the consistency of cheese-rind, and of use in the 
MACKEREL SHARK, WITH REMORA ATTACHED 
2. HAMMER-HEAD SHARK. 
anatomy of animals for sustaining or connecting 
softer parts. The external ear of man consists 
chiefly of a convoluted wing of cartilage covered 
with skin. The so-called “breast-bone” of man 
is a tree-like development of cartilage designed 
to bridge together the outer ends of the principal 
ribs, protect with some firmness the vital organs 
within, and yet permit the rise and fall of the chest 
in breathing. 
The Cartilaginous Fishes, embracing the sharks, 
rays, skates and intermediate forms, 
are those whose skeletons are largely 
composed of plates and stems of car- 
tilage, or gristle and but little bone. 
Instead of bony rays, the fins of 
these creatures are supported by 
cartilaginous rays so closely joined 
together that they form plate-like 
structures. 
General Characters of Sharks. — 
With few exceptions, sharks have ex- 
ternally the same general form as the 
typical fishes. Instead of broad, flat 
scales that overlap each other like 
shingles, their scales are very mi- 
nute, horny, sharp-pointed and closely 
packed together. When the skin of 
a shark is stroked from head to tail, 
it feels like a hair-cloth sofa, but when 
stroked the other way, it is like the 
sharpest sand-paper. For centuries 
shark-skin has been used for smooth- 
ing and polishing wood and other 
substances; and when prepared for 
that use it is called “shagreen.” 
Instead of one very large gill-open- 
ing, as in typical fishes, a shark has 
usually five small slits in the skin be- 
hind the gills, which are capable of 
being tightly closed. In nearly all 
species the mouth is situated under- 
neath the head, and often it is of 
enormous proportions. The jaws are composed 
of cartilage, the teeth are usually triangular, and 
set along the edge of the jaw, in rows, crosswise 
with the edge of the mouth. Behind each active 
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